1. Technical Field
The present invention relates in general to improvements in mobile data terminals and in particular to improvements in an external radio frequency antenna for utilization with a mobile data terminal. Still more particularly, the present invention relates to a flexible external radio frequency antenna which may be rapidly and efficiently affixed to a mobile data terminal.
2. Description of the Related Art
Distributed data processing systems are increasingly common in the modern electronic work place. Such distributed data processing systems may include thousands of computers or workstations including main frame computers, so-called "personal" computers, and modern state-of-the-art portable or "laptop" computers. In modern distributed data processing systems many such computers may be linked together utilizing various topologies and different types of networks including Advanced-Peer-To-Peer-Networks (APPN), Local Area Networks (LAN) or various other types of networks. While in the past computer networks are generally coupled together utilizing existing telephone land line systems, or specialized wiring, modern distributed data processing systems often utilize more sophisticated means of communication.
For example, the increasing efficiency and decreasing cost of cellular communication equipment has resulted in the utilization of that technology to couple together multiple computers without the necessity of access to a telephone line outlet. This particular technology is particularly effective in combination with small, portable battery powered laptop or notebook computer in which the necessary modem and cellular communication circuitry are miniaturized and provided in an integral fashion with the computer itself. Often in such a computer, it is possible to remove the fixed disk drive and replace that subassembly with a combination modem and cellular communications device such that the data processing terminal may be coupled to a large network utilizing cellular communications technology. Thus, an operator utilizing such a computer may initiate communications and transfer data between his or her computer and a distributed data processing system without the necessity of access to either telephone lines or power lines.
The increasing utilization of such devices and the after market refitting of existing laptop or notebook type computers with such communications modules result in a problem in the efficiency of the radio frequency communication. That is, devices which are initially designed for utilization with cellular communication circuitry are constructed with internal antenna elements which are optimized for cellular communications; however, the after market refitting of a laptop or notebook computer with a combination modem and cellular communication device often causes a problem, since such devices were not designed initially for cellular communication network linking.
The antenna devices typically utilized for cellular communication generally compose multiple antenna elements, each including a radiating element which is equal in length to some fraction of the wavelength generally utilized by the cellular communication device. Further, in order to enhance the efficiency of communication, these multiple antenna elements must include elements which are separated by a minimum distance and preferably must be oriented normal to each other in space, in order to provide the necessary separation and spatial diversity.
Thus, upon reference to the foregoing it should be apparent to those skilled in the art that a need exists for an external antenna which may be rapidly and efficiently affixed to a portable data processing terminal in a manner which provides optimum radio frequency communication.